id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	tournament_has_players_double	NULL	ref	PRIMARY,fk_tournament_has_players_double_players_double_id	PRIMARY	4	const	4	75	Using where; Using filesort
1	SIMPLE	players_double	NULL	eq_ref	PRIMARY,fk_players_double_player_1_id,fk_players_double_player_2_id	PRIMARY	4	playtennis_dev.tournament_has_players_double.players_double_id	1	43.75	Using where